I. Field
The present disclosure relates generally to communication, and more specifically to techniques for performing handover between wireless communication networks using different radio access technologies.
II. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These networks may be multiple-access networks capable of supporting communication for multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, and Frequency Division Multiple Access (FDMA) networks. A CDMA network may implement a radio access technology (RAT) such as cdma2000 or Wideband-CDMA (W-CDMA). cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a RAT such as Global System for Mobile Communications (GSM). W-CDMA and GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP). cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various RATs and standards are known in the art.
Data usage for wireless communication networks continually grows due to increasing number of users as well as emergence of new applications with higher data requirements. Consequently, new wireless networks with enhanced performance are continually developed and deployed. Second-generation (2G) wireless networks such as GSM and IS-95 networks can provide voice and low rate data services. Third-generation (3G) wireless networks such as Universal Mobile Telecommunication System (UMTS) networks (which implement W-CDMA) and CDMA2000 1X networks (which implement IS-2000) can support concurrent voice and data services, higher data rates, and other enhanced features. Next generation wireless networks will likely provide higher performance and more features than existing 2G and 3G wireless networks.
A major challenge in development and deployment of a new wireless network is interoperability with existing wireless networks. It is desirable for a wireless user to be able to roam seamlessly between the new wireless network and existing wireless networks. This would allow the user to enjoy the performance advantages of the new wireless network and the coverage benefits of the existing wireless networks.